Active matrix organic light emitting diode (AMOLED) panels become a preference for future display technology due to their advantages such as high picture quality, short response time of moving image, low power consumption, wide viewing angle and super light and thin profile. In the backboard technology for AMOLED, technologies for manufacturing polycrystalline silicon layers include various manufacturing methods, such as excimer laser annealing (ELA), solid phase crystallization (SPC) and metal induced crystallization (MIC). Currently, a method capable of mass production of active layers in transistors for backboards is the excimer laser annealing (ELA) method.
The excimer laser annealing (ELA) process is a relatively complex annealing process. In a polysilicon film, controlling grain size and grain uniformity has always been a research hotspot in this technical field, because the amount and distribution of polysilicon crystal grains covered by a channel region of a low temperature polysilicon film transistor, namely, the uniformity issue, would directly influence the electricity performance of the low temperature polysilicon film transistor, such as magnitude of mobility, uniformity of mobility and threshold voltage.
Thickness distribution of an amorphous silicon film is generally non-uniform. An amorphous silicon film is generally thinner in the middle than at edge, or thicker in the middle than at edge. Even for an amorphous silicon film with good uniformity, the film thickness varies.
Therefore, how to control amorphous silicons to become ideal polysilicons, namely, making a polysilicon film have large size and uniformly distributed grains, has been a technical challenge difficult to resolve.